There is known an air cell, for example, as described in Japanese Unexamined Patent Application Publication No. 03-037972. The air cell described in Japanese Unexamined Patent Application Publication No. 03-037972 includes a flat battery case composed of a plurality of parts, air cathodes (positive electrodes) placed on front and back surfaces of the battery case, and an anode (a metal negative electrode) housed in the battery case. The air cathodes detachably installed in the battery case push rubber gaskets or the like provided in the battery case so as to be sealed therein. Similarly, the anode detachably housed in the battery case is inserted from a side portion of the battery case so as to be sealed therein in the same manner as the air cathodes. Namely, the air cathodes and the anode push the rubber gaskets or the like to keep the sealing performance for convenience of replacement.